Unusual presentation of metastatic amelanotic melanoma of unknown primary origin as a solitary breast lump.

Breast is an uncommon site for metastasis from other malignancies especially melanomas. A 40-year-old lady presented with a rapidly growing, painless, solitary breast lump for 3 months. Past history was unremarkable for skin lesions, biopsy or any surgery. The lump was hard and freely mobile with normal overlying skin, nipple, and areola. Careful examination of the skin did not reveal any lesion. Grossly the tumor was partially circumscribed and gray white. Microscopically, a highly cellular lesion was seen showing nests and sheets of large anaplastic cells with atypical mitotic figures without any evidence of cytoplasmic pigment. Immunoreactivity for S-100 and HMB-45, confirmed the diagnosis of amelanotic melanoma. It is important to be aware of this atypical presentation of amelanotic melanoma in the breast and to utilize immunohistochemistry to differentiate from other commoner high-grade malignant tumors.